Flexural Behaviour of Prestressed Post-Tension Voided Biaxial Slab Under Uniformly Distributed Load

Abstract

This study examines the flexural behavior of prestressed post-tensioned voided biaxial slabs under uniformly distributed loads (UDL) to evaluate structural performance, quantify material efficiency, and validate finite element models. Four full-scale slabs—solid and voided, with and without post-tensioning (PT)—were experimentally tested under UDL using a multi-level steel beam system to simulate uniform loading. Parameters such as crack initiation, deflection, and failure modes were monitored. Nonlinear finite element analysis (FEA) in ANSYS, employing Solid65 and Link180 elements, replicated material behavior and boundary conditions. The results showed that PT-voided slabs retained 96% of PT-solid yield capacity while reducing concrete volume by 22%, achieving a 21% self-weight reduction. Post-tensioning enhanced stiffness by 21% compared to non-PT voided slabs and delayed crack initiation. FEA predictions closely matched experimental data, with ≤10% deviation in load-deflection responses and consistent crack patterns. The novelty lies in demonstrating that PT effectively mitigates stiffness reductions (6% vs. PT-solid) caused by cuboidal voids, enabling high-performance, lightweight designs. This integration of PT with voided systems offers a sustainable solution, reducing material usage by up to 22% while maintaining structural integrity, thereby advancing eco-efficient construction practices. Findings provide critical insights for optimizing voided slab applications in modern infrastructure.